This invention relates to an electrophotographic image carrier and an image forming apparatus, an image forming method and a processing cartridge using the image carrier.
Recently, an electrophotographic image forming method is popularly used for writing digital processed data, in which an organic photoreceptor is exposed to light doted image wise to form a static latent image on the image carrier comprising a photoreceptor and an image is formed by a reversal development.
It is required to the electrophotographic image carrier comprising the photoreceptor to be used in such the method that the photoreceptor is stable for a prolonged period of time of use and is able to correspond to writing of a high-resolution image. Usually, an organic photoreceptor, also referred to OPC, is an essential technology for a process requiring a high image quality since the organic photoreceptor can be selected from a great choice of materials, compared with an inorganic photoreceptor. Accordingly, the organic photoreceptor can easily be corresponded to various kinds of light source and is excellent in the stability of charged potential.
On the other hand, the organic photoreceptor is required to be improved in the durability thereof since the organic photoreceptor is low in the mechanical strength and a defect caused by a wearing or a damage. The use of a protective layer formed by cross-linked a siloxane resin, which is excellent in the mechanical strength, is noted as a technology by which the resistivity of the organic photoreceptor to the problems of damage and wearing can be raised.
Various trial have been carried out to solve such the problems. For example, a technology in which a condensation product of an organic silicon polymer and colloidal silica is contained in the surface layer is disclosed in Japanese Patent Publication Open to Public Inspection No. 9-319130.
Recently, as described in Japanese Patent Publication Open to public Inspection (JP O.P.I.) 9-190004, a photoreceptor is developed which has a resin layer containing a siloxane resin having a charge transportable structural unit. Such the protective layer is superior in the mechanical strength and the electric property, and the drawback of the mechanical strength of the organic photoreceptor can be considerably improved thereby. However, the effect of such the layer is insufficient yet in the durability and the image quality.
Besides, it has been known that the charge transporting substance in the properties of the photoreceptive layer is deteriorated by an oxidant gas such as ozone or NOx formed by an electrode for charging, transferring or separating. The oxidation of the photoreceptor causes lowering in the charging property and the light sensitivity, consequently a fault in the image such as fogging or lowering in the image density is occurred. However, the deterioration is apparently inhibited in an usual photoreceptor since the photoreceptive layer is suitably worn and the extreme surface, which is mostly deteriorated, is suitably worn and the deteriorated substance and the contamination substance on the surface is removed. In contrast, in the photoreceptor having the resin layer containing the siloxane resin having the charge transportable structural unit, the mechanical strength and the electrophotographic property of the photoreceptor can be raised by the strength of the siloxane resin and the presence of the charge transportable unit and an advantage that the wearing amount of the photoreceptor is extremely reduced. However, the reduced wearing amount of the photoreceptor makes difficult to remove the effect of the contamination substance formed by the effect of the oxidant gas such as ozone or NOx. Accordingly, it is strongly required to inhibit the deterioration under the condition in which the wearing is difficultly occurred.
It is pointed out that the problems of deterioration in the stability of charged potential of the photoreceptor and the image quality are caused by accumulation of the deteriorated substance formed by the oxidant gas such as ozone and NOx in a prolonged period of time since the siloxane resin having a cross-linked structure excellent in the surface strength is lowered in the wearing amount. The invention is carried out to solve such the problems.
As a result of the studying by the inventors, it is a problem of the cross-linked layer of organic silicon that the layer is easily influenced by the absorbed moisture under a high humid condition since a not reacted hydrolyzable group or a silanol group tends to be remained on the layer surface. When a large amount of not reacted group exists, absorption of water molecules and formation of a product of discharge in the charging process tend to occur under a high humid condition. Consequently, the surface electric resistivity is lowered and a problem such as image flowing is caused.
The above-mentioned phenomena are considerably occurred at a portion near the charging electrode when the image carrying drum is stopped. For example, the image flowing cannot be sufficiently inhibited at the portion under the charging electrode by blowing exhausted air or a heating device arranged at a portion near the image carrying drum. It is considered that the damaging substance such as active oxygen formed in the operating period is remained around the charging electrode and affects to the photoreceptor coated on the stopped image carrier. Accordingly, the surface of the image carrier cannot be uniformly heated by usual blowing of the exhaust air or by the separated heating device arrange at near the image carrier, and effect of such the heating means may be insufficient to prevent the absorption of water molecules under the high humid condition.
The object of the invention is to provide an electrophotographic image carrier comprising a photoreceptor, in which the effects of the resin layer containing a siloxane resin having a cross-linked structure is maintained during a prolonged period of time, and which has a good charging property, a high sensitivity and a high image quality, and the charged potential thereof is stable in the course of use for a prolonged period of time, and to provide an image forming apparatus, an image forming method and a processing cartridge using the image carrier.
The another object of the invention is to provide an electrophotographic image carrier which has a good charging ability, a high sensitivity and a high wearing resistivity, and the surface resistivity thereof is not lowered under a high humid condition, consequently the problem of image flowing is not occurred, and to provide an image forming apparatus, an image forming method and a processing cartridge each using the electrophotographic image carrier.
The inventors have found that the deterioration of the resin layer can be effectively inhibited when the resin layer has a charge transportable structure and contains an anti-oxidant, particularly an anti-oxidant having a specific structure.
An electrophotographic image carrier comprising an electric conductive substrate provided thereon, a photoreceptor comprising a photoreceptive layer and a resin layer, in which the resin layer comprises a siloxane resin having a charge transportable structural unit and a cross-linked structure, and the resin layer contains an anti-oxidant.
An electrophotographic photoreceptor comprising a resin layer which comprises a siloxane resin having a cross-linked structure which is formed by reacting an organic silicon compound having a hydroxyl group or a hydrolyzable group with a compound having a charge transportable structural unit, and the resin layer contains an anti-oxidant.
The electrophotographic photoreceptor wherein the resin layer comprises a siloxane resin having a cross-linked structure represented by the following Formula 1. 
wherein X is a structural unit having charge transportability, and Z is an optional linking group having two or more valences.
The electrophotographic photoreceptor wherein Z in Formula 1 is a substituted or unsubstituted alkylene group or a substituted or unsubstituted arylene group.
The electrophotographic photoreceptor wherein Z in Formula 1 is an atom or a group each having two or more valences when the adjacently bonded atoms (the silicon atom Si and the carbon atom C constituting a part of the charge transportable structural unit) are removed.
The electrophotographic photoreceptor wherein Z in Formula 1 is O, S or NR, and R in Formula 1 is H or a mono-valent organic group.
An electrophotographic photoreceptor comprising a resin layer which comprises a siloxane resin having a cross-linked structure which is formed by reacting an organic silicon compound having a hydroxyl group or a hydrolyzable group with a compound having a charge transportable structural unit which has a hydroxyl group, and the resin layer contains an anti-oxidant.
The electrophotographic photoreceptor, wherein the anti-oxidant is a hindered phenol compound.
The electrophotographic photoreceptor, wherein the anti-oxidant is a hindered amine compound.
The electrophotographic photoreceptor, wherein the anti-oxidant is an organic phosphor anti-oxidation compound.
The electrophotographic photoreceptor wherein the anti-oxidant is an organic sulfur anti-oxidation compound.
The electrophotographic photoreceptor, wherein the resin layer is arranged as the outermost layer.
An image forming method using the electrophotographic image carrier comprising photoreceptor, which comprises the steps of charging, image wise exposing, developing, transferring and cleaning.
An image forming apparatus comprises the electrophotographic image carrier and processes of charging, image wise exposing, developing, transferring and cleaning.
A processing cartridge to be used for image forming through the processes of charging, image wise exposing, developing, transferring and cleaning in which the processing cartridge comprises a combination of the electrophotographic image carrier with at least one of a charging device, an image exposing device, a developing device, a transferring device and a cleaning device.
An electrophotographic image carrier comprising a photoreceptor having a layer containing a siloxane resin having a cross-linked structure.
The electrophotographic image carrier wherein the layer containing the siloxane resin having the cross-linked structure is a resin layer formed by reacting an organic silicon compound having a hydroxyl group or a hydrolyzable group with colloidal silica.
The electrophotographic image carrier, wherein the photoreceptor contains a layer containing a siloxane resin having a charge transportable structural unit and a cross-linked structure.
The electrophotographic image carrier, wherein the photoreceptor contains a layer containing a siloxane resin having a charge transporting ability and a cross-linked structure.
The electrophotographic image carrier, wherein the siloxane resin having a charge transporting ability and a cross-linked structure is a siloxane resin formed by reacting an organic silicon compound having a hydroxyl group of a hydrolyzable group with a compound having a structural unit which has a hydroxyl group and a charge transporting ability.
The electrophotographic image carrier, wherein the layer containing the siloxane resin having the charge transporting ability and the cross-linked structure contains an antioxidant.
The electrophotographic image carrier, wherein the layer containing the siloxane resin having the charge transporting ability and the cross-linked structure contains a hindered phenol compound or a hindered amine compound as an antioxidant.
The electrophotographic image carrier, wherein the layer containing the siloxane resin having the cross-linked structure is a surface protective layer.
The electrophotographic image carrier wherein the image formation is carried out while heating the photoreceptor by a heating device from the interior of the photoreceptor.
An image forming method wherein the electrophotographic image carrier is used and the method comprises the step of heating the electro-photographic image carrier.
The image forming method wherein the step of heating the electrophotographic image carrier is carried out from the interior of the photoreceptor thereof.
An image forming apparatus wherein the electro-photographic image carrier is used and an image is formed through the processes of charging, imagewise exposing, developing, transferring, separating and cleaning.
A processing cartridge to be used for forming an image using the electrophotographic image carrier and through processes of charging, imagewise exposing, developing, transferring, separating and cleaning, wherein the processing cartridge comprises a combination of the electrophotographic image carrier and at least one of a charging device, an image exposing device, a developing device, a transferring or separating device and a cleaning device.